# Federal Register Search API

> Federal Register Search API is a paid API for AI agents from anibalb.duckdns.org, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-31).

Search and retrieve U.S. Federal Register documents including rules, notices, and proposed rules, filtered by keyword query

## Facts

- Endpoint: GET https://anibalb.duckdns.org/x402/federal-register?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/federal-register-search-api-d4c7cf7a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5zmVj3X_J3500NeEnvjoW

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability federal-register-search-api-d4c7cf7a
```

Example prompt: Search the Federal Register for all rules and notices related to 'stablecoin' and give me the top results with their agency names, abstracts, and citation numbers.

## When to prefer this

Use this endpoint when you need to search U.S. Federal Register documents by keyword to find rules, proposed rules, or notices from federal agencies. Prefer this over general web search when you need structured regulatory data with official FR citations, agency attribution, and publication dates — especially for legal research, compliance monitoring, or policy analysis.

## Known failure modes

- Missing or empty query parameter returns error or empty results
- Query too broad may return thousands of results with limited pagination
- Federal Register API downtime causes upstream failure
- No results found for highly specific or misspelled queries
- Rate limiting or payment failure if USDC balance insufficient

## How this service works

Public data and utility APIs paid per call in USDC on Base (x402). No accounts, no API keys. 174 routes: crypto/equity data, onchain reads, DNS/email/security intel, geo/weather, x402 payment diagnostics, dev utilities and more.

## Output

Returns a JSON object with the total count of matching documents, the number returned, the search query used, and an array of result objects each containing document type, title, agency name, abstract, Federal Register citation (e.g. '88 FR 12345'), and publication date.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "n": 3,
  "count": 6225,
  "query": "bankruptcy",
  "results": [
   {
    "type": "Rule",
    "title": "...",
    "agency": "...",
    "abstract": "...",
    "citation": "88 FR 12345",
    "publication_date": "2026-10-01"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/federal-register-search-api-d4c7cf7a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from anibalb.duckdns.org](https://www.zero.xyz/host/anibalb.duckdns.org/llms.txt)